What is ISO?
In Digital Photography, the ISO rating or number is an indicator of how sensitive a camera’s image sensor is to light at a specific setting. Changing your camera’s ISO setting will amplify or decrease the image sensors’ ability to read light during exposure.
When your camera is set to a higher numbered ISO such as 800, less light is needed to obtain a correct exposure than if the camera is set to 100 for the same shot. That is, assuming other factors such as the camera lens aperture setting, and the shutter speed setting remains the same.
Pixel density is pretty easy to figure out. A typical point-and-shoot camera has an image sensor that is 4.6 by 6.2 millimetres in size—that’s really, really small. A typical APS-C D-SLR has a sensor that is 18 by 24 millimetres. If both cameras have the same resolution, like the 16-megapixel Sony Alpha NEX-C3 and the inexpensive Canon PowerShot A2400 IS, the pixel density of the camera with the physically larger image sensor is much lower, giving it an innate edge at higher ISOs.
How to Choose a better ISO setting in Camera or Mobiles?
Higher the number is generally used in darker situations to get faster shutter speeds. For example, an indoor sports event when you want to freeze the action in lower light.
100 ISO is generally accepted as normal and will give you lovely crisp shots (little noise/grain).
Most people tend to keep their digital cameras in ‘Auto Mode’ where the camera selects the appropriate ISO depending upon the conditions you’re shooting in (it will try to keep it as low as possible) but most cameras also give you the opportunity to select your own ISO also.
“Tips to Click Better Photos”
1) During the daytime in sunny conditions when photographing a subject covered by the shade of a tree, Usually, it always set to 400 for starters. Once you set camera ISO, place your eye to the rear vision and go to take a shot. When you do this, you look along the sides of the screen for the shutter speed. The purpose of this is to make sure the shutter speed is faster than the mm length of the lens.
2) Nighttime walking around the streets taking snapshots without a tripod set your camera ISO to 800 for starters. It is the only way to get a sharp night photo while hand holding the camera. This also presumes there is plenty of street lighting available and your Aperture f-number is the lowest possible.
3) Use it 100 when photographing landscapes that I intend to print out as fine art. Unless it is a sunny day, the shutter speed will be slower, however, the image quality will be perfect. There are many reasons why photographers intentionally set a slower ISO speed in low light. For example, you can slow down flowing water, or show motion in a moving object. For times like these, you would choose the lowest number as possible.
Generally speaking, the majority of new cameras coming out today can easily shoot at ISO 400 and not have any visible image quality issues. It can help you to know how to use the camera in low or high light.